Angus Sires Research Articles

Association of the muscle hypertrophy locus with carcass traits in beef cattle.

A locus near the centromere of bovine chromosome 2 is responsible for muscle hypertrophy (mh) in cattle. The objectives of this study were to refine the genomic region in which the locus resides and to assess the effects of a single copy of the mh allele on carcass and birth traits. Two half-sib families were developed using a Belgian Blue x MARC III (n = 246) or a Piedmontese x Angus (n = 209) sire. Traits analyzed were calving ease (CE), birth weight (BWT, kg), longissimus rib eye area (REA), retail product yield (RPYD), USDA yield grade (YG), marbling (MAR), fat thickness (FAT), estimated kidney, pelvic, and heart fat (KPH), and longissimus tenderness measured as Warner-Bratzler shear force at 3 (S3) and 14 (S14) d postmortem. Six microsatellites were used to determine the presence or absence of the mh allele and to confirm the location of the locus affecting the traits, which was assessed to be 4 cM from the beginning of the linkage group, with the 95% confidence interval between 2 and 6 cM. Cattle with an mh allele had increased (P < .01) REA, RPYD, and BWT and decreased MAR, YG, FAT, and KPH, compared with those without the allele. The effects of the mh allele (mh/+ vs +/+) were 1.35, 1.6, .41, -1.01, -1.42, -.84, and -.86 residual standard deviations, respectively. There were no effects (P > .10) for CE, S3, and S14. Allelic differences due to the mh locus were similar for both sources (Belgian Blue or Piedmontese). Individuals inheriting a single mh allele had a leaner, more heavily muscled carcass compared with those inheriting the alternative allele. Thus, mating schemes that maximize production of mh/+ genotypes provide a viable approach for improving carcass composition.

Germplasm evaluation in beef cattle-cycle IV: birth and weaning traits.

Gestation length, unassisted calving percentage, perinatal mortality, calf crop weaned (survival from birth to weaning), birth weight, and 200-d weaning weight of 2,597 calves born and 2,433 calves weaned are reported for F1 crosses resulting from matings of Angus, Hereford, Charolais, Gelbvieh, Pinzgauer, Shorthorn, Galloway, Longhorn, Nellore, Piedmontese, and Salers sires to Angus and Hereford dams (> or = 3 yr of age) in Cycle IV of the Germplasm Evaluation (GPE) Program at the U.S. Meat Animal Research Center. Hereford and Angus sires included 1) reference sires born from 1963 to 1971 used in previous cycles of the GPE Program, 2) sires born from 1982 to 1985 (1980s), and 3) sires born from 1983 to 1985 used in natural service clean-up matings. Effects of sire breed of calf were significant for gestation length, unassisted calving percentage, birth weight, and 200-d weaning weight. Gestation length was significantly longer for Nellore than for Charolais, Galloway, Longhorn, Piedmontese, and Salers, which were in turn longer than for Hereford-Angus and Shorthorn. Rankings for birth weight tended to be inversely related to those for calving ease, except for Shorthorn and Salers sires, which required low assistance relative to their heavy birth weights. Rankings for 200-d weight among AI-sired progeny were as follows: Charolais (231.3), Nellore (229.7), Salers (225.5), Shorthorn (223.8), 1980s Hereford-Angus (223.1), Piedmontese (220.0), Galloway (209.5), reference Hereford-Angus (210.1), and Longhorn (199.0); differences > or = 6.5 kg were significant.

Growth, reproduction, and carcass and meat quality characteristics of once‐bred Hereford × Friesian and Simmental × Friesian heifers managed for low or high liveweight gain during mid pregnancy

Abstract The growth, reproduction, carcass and meat quality characteristics of once‐bred Hereford × Friesian (H × F) and Simmental × Friesian (S × F) heifers mated to Angus sires and managed for high gain (HG” group) or low gain (LG” group) during mid pregnancy (i.e. pregnancy days 114–214 = P114‐P214) were compared in this study. Liveweights at mating of S × F heifers (347 ± 6 kg) were slightly higher (P < 0.10) than those of H × F heifers (333 ± 5 kg). From P114 until P214, HG heifers had significantly higher (P < 0.001) growth rates (0.72 ± 0.03 kg/day) than the LG group (0.16 ± 0.02 kg/day). This resulted in a higher liveweight in HG heifers at P214 (P < 0.001) and P270 (P < 0.01) than in the LG heifers. Gestation length, calving score, and liveweight loss at calving were not influenced by dam genotype or mid‐pregnancy liveweight gain. Liveweight gain of the 24 heifers that suckled calves was not affected by dam genotype or prior liveweight gain of the dam during the suckling period or from weaning ...

Herbage intake, growth performance, and carcass and meat quality characteristics of once‐bred Hereford × Friesian heifers weaned at 12 or 21 weeks of lactation

Abstract Beef‐breeding cows are traditionally weaned at about 7–8 months of calf age in New Zealand but early weaning may have advantages in once‐bred heifer beef production systems. This study compared the growth performance, and carcass and meat quality characteristics, of 31 once‐bred Hereford × Friesian heifers mated to Angus (17 heifers) or Charolais (14 heifers) sires from which calves were removed at either 12 weeks (Day 84 of lactation = L84) or 21 weeks (Day 147 of lactation = L147) of lactation. These are referred to as the “W84” (calves weaned at Day 84 and their dams) or “W147” (calves weaned at Day 147 and their dams) groups respectively. During L84‐L147, W84 heifers had higher daily liveweight gain (LWG) than the W147 heifers (0.79 versus 0.51, PSE = 0.07 kg/day, P < 0.01). Calves weaned at L84 had significantly lower daily LWG than W147 calves during the period L84‐L147 (0.73 versus 1.30, PSE = 0.05 kg/day, P < 0.001). This resulted in 30 kg lower (P < 0.001) liveweight in W84 versus W147 c...

Lipogenic activity of intramuscular and subcutaneous adipose tissues from steers produced by different generations of angus sires

Simmental and Hereford cows (n = 74) were inseminated with semen from purebred Angus bulls from the 1960s or with semen from purebred Angus bulls from the 1980s. The F1 calves provided the foundation for two investigations, one addressing growth and carcass characteristics, and another measuring the impact of sire generation on lipid metabolism and adiposity. Calves sired by the 1980s-type bulls had greater (P < .05) birth, weaning, and final live weights and carcass weights. They also had larger (P < .05) hip heights and hip widths at weaning and larger (P < .05) hip heights and lower (P < .05) body condition scores at slaughter. There were no differences (P > .05) in any measure of fatness between groups (adjusted fat thickness, kidney, pelvic, and heart fat, or marbling scores), but yield grade was higher numerically (P < .1) for the 1980s steers. The second aspect of this research addressed the influence of different generations of Angus sires on specific carcass traits and adipose tissue metabolism. A subset of six steers for each generation type (from Simmental cows) were selected and samples were collected at slaughter for measurements in vitro. For both generation types, intramuscular (i.m.) adipocytes had lesser (P < .05) cell volumes than subcutaneous (s.c.) adipose tissue. Correspondingly. i.m. adipose tissue exhibited lower (P < .05) rates of 14C-labeled acetate incorporation into lipids as measured immediately after slaughter. Intramuscular and s.c. adipocytes from 1980s-type steers were smaller (P < .05) than those from the 1960s-types steers, with correspondingly more cells per gram of tissue.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of sire and dam on late-pregnancy conceptus and hormone traits in beef cattle.

Forty-six primiparous F1 heifers produced from mating Brahman (B), Charolais (C), Jersey (J), Longhorn (L), or Shorthorn (S) sires to crossbred cows were bred by AI to one of two Angus sires selected to produce high (H) or moderate (M) fetal growth. Dams were slaughtered at an average of 231 d of gestation. Daily blood samples were obtained from the dam on d 228 to 231 to determine serum estradiol, progesterone, and testosterone concentrations. Pelvic height was greatest (P < .05) in B, C, and L and pelvic width was greatest (P < .05) in S, C, and J dams, but pelvic areas did not differ (P > .10). Dams with greater hip height had larger pelvic areas (r = .45; P < .01). Intact fetuses from C and S dams were heaviest (P < .05), those from S dams had the greatest (P < .05) head width, and heart girth was greatest (P < .05) in fetuses from L dams. Fetuses from H sires were greater in weight (P < .01), body length (P < .01), and cannon circumference (P < .01). Dam differences were found in fetal heart weight (P < .01), trimmed placental membrane weight (P < .01), and average placentome weight (P < .05). Weights of eviscerated fetuses were greatest from C dams (P < .05). Placentome number was lowest (P < .05) in J dams, but J dams had the highest (P < .05) average placentome weight. Interactions between fetal genotype and breed of maternal environment were found for weight of eviscerated fetus (P < .05), body length, and heart weight (P < .01) and resulted from both magnitude and direction of change in the sire effect. The H sire increase in fetal weight was greatest in J dams, whereas B dams allowed expression of the fetal growth potential but at a lower level. Fetal trait interactions were also found for breed x sex and sex x sire (P < .05 to P < .01) and were due to the magnitude of differences expressed between the M and H sires. Serum testosterone concentrations were highest (P < .05) in B and L dams, dams gestating fetuses sired by the H sire (P = .08), and those with male fetuses (P < .01). We interpret these results to indicate that some maternal environments can suppress fetal growth, whereas others seem to complement the growth and allow maximum expression of the fetal genetic growth potential.(ABSTRACT TRUNCATED AT 400 WORDS)

Aspects of heifer management which limit productivity on dairy farms in Western Australia: a survey

In 1989, a survey of 53 producers from the major dairy areas of the south-west of Western Australia was conducted to determine current management practices for dairy heifers and to identify of areas of heifer management which could be improved to increase overall farm productivity. Total farm size averaged 220 ha, with an average market milk quota of 699 L/day (50% of total milk produced). One-third of producers described their farm activity as dairying only. Some 116 calves were born per farm, with a year-round calving distribution. Calves were fed 5.4 L whole milk/day, with an average age at weaning of 13 weeks (range 5-26 weeks). Mortality recorded to 3 months of age was 4% and the most important health problem associated with calf rearing was scours. Of those properties with a health problem, 25% used antibiotics on a regular basis. All producers provided supplementary feed pre-weaning. In the period between weaning and mating, more than half the producers ran heifers on paddocks 3-80 km distant from the main farm, with hay the most common form of supplementary feed. Most dairy heifers were naturally mated to Hereford, Friesian, or Angus sires; hence, few heifers from first calvers were kept as dairy replacements. Average age at first calving was reported to be 30 months, with 1 in 9 heifers culled post-calving, generally for low milk production. The survey highlighted several aspects of heifer management with the potential to improve overall productivity of dairy farms in Western Australia. They include earlier weaning, strategic use of antibiotics to prevent the development of antibiotic resistance, greater use of artificial insemination, and a reduction in age at first calving.

Contribution of breed, cow weight, and milk yield to the traits of heifers and cows in four beef breeding systems.

Measurements were taken on 216 cows with 469 calvings for weight at weaning, condition at weaning, milk yield, milk fat percentage, milk lactose percentage, milk protein percentage, dry period feed intake, lactation period feed intake, total feed intake, first-service pregnancy rate, pregnancy rate, and days to pregnancy. Measurements were also taken on 183 heifers for first-service pregnancy rate, days to pregnancy, and age at first calving. The data spanned the years 1980 to 1988; animals belonged to one of four breeding systems: Hereford, small rotation (Angus, Gelbvieh, Pinzgauer, Tarentaise), large rotation (Charolais, Maine Anjou, Simmental), and Angus-large rotation (cows with Angus sires and large-rotation dams). Maine Anjou-sired cows had lower annual feed intake and Charolais-sired heifers lower first-service pregnancy rate than the other large-rotation breeds. Gelbvieh-sired cows had lower milk lactose and protein percentages than the other small-rotation breeds. Within breeding system neither cow weight nor milk yield were significantly associated with reproductive traits of cows. No differences among breeding systems in associations between feed intakes and weights or milk yields were detected.

Prediction of lean content in the carcasses of beef cattle. II. From measurements of specific cuts

Carcass data on 304 steers and 320 heifers from seven breed of dam groups were analyzed to test equations for predicting weight and proportion of lean content in beef carcasses from measurements of specific cuts. All dams were bred to Angus sires for first calving and to a Simmental sire for second and third calvings. Cattle by Angus sires were slaughtered at 10-mm backfat thickness evaluated ultrasonically; those by the Simmental sires at 7 mm. One side of each carcass was cut into eight cuts and separated into fat, lean and bone. Data were analyzed by multiple stepwise regression procedures. Prediction equations from each cut were obtained from the overall data and subpopulations by breed of sire, by sex and by breed of dam group. Cold-carcass weight accounted for the highest proportion of variation of lean weight in the side of the carcass, but it accounted for no more than 3% of the variation of proportion lean. Lean weight in hip and chuck, particularly in hip, was a most important predictor for estimating lean weight of the side. Total weights of each cut were also important predictors. Proportion lean in each cut alone was the strongest predictor of proportion lean in the carcass. Proportions of weights of cut in the carcass were also important predictors. Predictions of lean content (weight and proportion) in the carcass from dissected cuts of chuck and hip provided the most precise estimates. Average biases for breed of sire–degree of finish combinations, sex or breed of dam group were relatively small when an overall equation based on information from the hip was used. Key words: Beef, prediction of lean content, carcass, cuts, breed, sex

Determining beef carcass retail product and fat yields within 1 hour postmortem

Hot carcasses from 220 steers (progeny of Hereford or Angus dams mated to Angus, Charolais, Galloway, Gelbvieh, Hereford, Longhorn, Nellore, Piedmontese, Pinzgauer, Salers, or Shorthorn sires) were used to develop equations to estimate weights and percentages of retail product (RP) and trimmable fat (TF) yields. Independent variables examined were 1) 12-13th rib fat probe (12RFD), 2) 10-11th rib fat probe (10RFD), 3) external fat score (EFS), 4) percentage of internal fat estimated hot (H%KPH), 5) hindquarter muscling score (HQMS), and 6) hot carcass weight (HCW). Right sides of the carcasses were fabricated into boneless retail cuts, trimmed to .76 cm of subcutaneous and visible intermuscular fat, and weighed. Cuts were trimmed to 0 cm of subcutaneous and visible intermuscular fat and reweighed. Multiple linear regression equations containing 12RFD, EFS, H%KPH, and HCW accounted for 95 and 89% of the variation in weight of total RP at .76 and 0 cm of fat trim, respectively. When weights of RP from the four primal cuts (.76 and 0 cm of fat trim) were the dependent variables, equations consisting of 12RFD, EFS, H%KPH, and HCW accounted for 93 to 84% of the variation. Hot carcass equations accounted for 83% of the variation in weight of total TF at both .76 and 0 cm of fat trim. Furthermore, equations from hot carcass data accounted for 54 and 51% of the variation in percentage of total RP and 57 and 50% of the variation in percentage of RP from the four primal cuts at .76 and 0 cm of fat trim, respectively. Hot carcass prediction equations accounted for 72% of the variation in percentage of total TF at both fat trim levels. Hot carcass equations were equivalent or superior to equations formulated from chilled carcass traits.

Biological type effects on gestation length, calving traits and calf growth rate.

Gestation length, birth weight calving difficulty, calf mortality rate at birth, calf mortality rate from birth to weaning, preweaning calf growth rate and calf 200-d weight were evaluated in a biological type study in which four sire breeds were bred by AI to Hereford dams. Angus and Red Poll sires represented breeds of medium size, and Pinzgauer and Simmental sires represented large breeds. Angus and Pinzgauer represented breeds with medium milk production, and Red Poll and Simmental represented breeds with high milk production. Dams mated to large sire breeds had longer (P less than .01) gestation lengths (.95 d) and higher calving difficulty scores than dams mated to medium-sized sire breeds. Calves from large sire breeds had heavier birth weight (P less than .01) and 200-d wt (6.1 kg; P less than .01) than calves from medium-sized sire breeds. Calf death loss and ADG to weaning were similar (P greater than .10) for all breeds of sire. Calves from the higher milk level sire breeds exceeded the medium-milk breeds in birth weight (1.3 kg; P less than .01) but did not (P greater than .10) in other traits. Calves from the higher milk level sire breeds exceeded the medium-milk breeds in birth weight (1.3 kg; P less than .01) but not (P greater than .10) in other traits. Interaction between size and milk production of sire breed existed for gestation length, birth weight, ADG from birth to weaning and 200-d calf weight (P less than .01). In general, mature size of sire breed was a good indication of expected performance traits not easily influenced by environment. Not all differences, however, could be explained by size and milk production of the size breed.

Preliminary carcass and meat research results from cycle IV of the cattle germ plasm evaluation program (1990)

Preliminary data representing two of five calf crops in Cycle IV of the Germ Plasm Evaluation Program are reported. Carcass and meat data from 454 steers produced by mating 11 sire breeds to Hereford and Angus dams were obtained. Hereford (H) and Angus (A) sires born in the late 1960's (original) and also 1982 to 1984 (new) were compared. Steers sired by the new sample of H and A sires were heavier at slaughter than those of original sires, whereas marbling and percentages of trimmed retail product (% TRP) have not changed. HA and AH had lower % TRP than most crosses. Longhorn crosses were lightest of all crosses and were average for % TRP and % Choice. Shorthorn crosses were similar to new HA and AH in % TRP and had a higher % Choice than all crosses. Piedmontese crosses were lighter and dressed higher than new HA and AH. A low percentage graded Choice, but they excelled in muscling, trimness, and % TRP. Steaks from Piedmontese crosses were more tender than those from most breeds. Salers crosses had similar weights, less fat, larger ribeyes, and higher % TRP than new HA and AH, but a lower % Choice. Ne110re crosses excelled in dressing percentage but had the least tender steaks. Breeds differed significantly in slaughter and carcass weights, dressing percentages, carcass composition, marbling, and meat tenderness. Breeds did not rank the same for marbling as they did for tenderness.

Estimation of milk consumption curve parameters for different genetic groups of bovine calves

ABSTRACTMilk consumption was estimated for crossbred suckled calves from birth to weaning during 2 years. Breed groups utilized were Aberdeen Angus (A) and Charolais (C) sires on Fl Angus-Hereford (and their reciprocals) dams in the 1st year and in the 2nd year, sires A and Nelore (Bos indicus) (N) were used on the same type of dam. The weigh-suckle-weigh technique was employed twice a day to estimate milk consumption on a weekly basis. Estimations were adjusted by least-squares for the effects of genetic group, week of estimation, and their interaction, with sex of calf and calf and cow weights in the week of estimation as covariables. Then a non-lineal regression equation of the form: y = b0Wb1e -b2b2W was fitted for each individual, where y = milk consumption and W = week of estimation. Curves for A and C were very close in their shape, but with a greater consumption (P &lt; 0·01) for C. For the 2nd year, there were differences among A and N both in the shape of the curve and in consumption at the peak of lactation (P &lt; 0·01). Differences in time to peak lactation were also found: for A calves, it was week 9, for C calves week 10 and for N calves week 3·8. The N group showed a sharper decline in persistency than the other groups, suggesting different patterns in milk consumption.

THE RELATIONSHIP OF SIRE EVALUATIONS FOR EASE OF CALVING AND BIRTH WEIGHT

Best Linear Unbiased Prediction procedures were used to evaluate 204 Beefmaster, Charolais, Simmental, Limousin, Red Angus and Chianina sires for birth weight (BW) and ease of calving (EC) based on the performance of a total of 6758 progeny. Correlations between BW and EC for sire means ranged from −0.77 to 0.08 with an average of −0.27 and for sire proofs they ranged from −0.90 to 0.14 with an average of −0.41. These results suggest that there is a strong relationship between the traits and that BW may be a valuable trait for use in indirect selection to reduce calving problems. Key words: Beef, ease of calving, birth weight, sire evaluation, correlation of sire proofs

ECONOMICS OF CALF PRODUCTION WITH FOREIGN CATTLE BREED CROSSES IN THE SHORT-GRASS PRAIRIES

The net farm income per Hereford-Angus unit dam (NFIPD) from calf production in the short-grass prairies was evaluated for calves of 31 three-breed crosses of foreign and British breeding. The data were from progeny produced near Manyberries, Alberta by utilizing Beefmaster and Red Angus sires for the first mating and Charolais (C), Simmental (S), Limousin (L) and Chianina (Chi) terminal sires for subsequent matings. There were 10 first-cross dam crosses consisting of Hereford (H) × Angus (A) as the control (HA), and nine dam cross combinations produced by mating C, S and L sires with H, A and Shorthorn (N) dams. There were 578 F1 females that entered the project, giving birth to 2079 calves and weaning 1866 calves during six consecutive years of the program. Rankings of the three-breed cross calves by NFIPD indicated that the L sire bred to a SA dam (LSA) and the C sire bred to a SA dam (CSA) returned the highest NFIPD. The next most profitable breed crosses were the LCN, LCH and CSH with NFIPD all within $15 of the LSA. The LH F1 dams were the least profitable with NFIPD up to $146 less than the LSA. The LH were followed by the LN and SN F1 female crosses for being unprofitable. The terminal sires ranked L = C &gt; S = Chi, the breed of sire of dam ranked C = S &gt; L, and the breed of dam ranked A &gt; H = N. The primary determinants of NFIPD differences among the breed crosses were birth weight, preweaning average daily gain, conception rates, calf deaths, calving rate, difficult calvings, and daily digestible energy requirements for the dam. Key words: Economics, cow-calf, foreign breeds, prairies

Reciprocal crossbreeding of Angus and Hereford cattle 2. Steer growth and carcass traits

Abstract Breed and heterosis effects for growth and some carcass characteristics were estimated from purebred Angus (A x A), purebred Hereford (H x H), and crossbred (H x A and A x H) steers bred at the Waikite Land Development Block near Rotorua over a 4-year period. Data from 477 steers alive at 5-month weaning and 445 steers slaughtered at 20 monthsof- age were analysed. Age of dam and age of calf were significant non-genetic effects for all liveweights, 20-month carcass weight, and eye muscle area. The age of dam effect was not significant for average fat depth over the 12th rib of the ~arcass, but age of calf showed a significant effect. At a constant slaughter age (618 days) steers by Hereford sires had a higher slaughter liveweight, carcass weight, and dressing-out percent than those by Angus sires. Steers out of Hereford cows relative to those from Angus cows were heavier at slaughter and had heavier carcasses but there was no significant effect of cow breed on other carcass traits. At a constant ...

Beef Production of Simmental × Angus and Hereford × Angus Cows Under Range Conditions2

A five-year study was conducted to compare reproductive performance, milk production and calf productivity of 180 Simmental × Angus (S × A) and Hereford × Angus (H × A) crossbred cows. Cows were managed on native range in western South Dakota with supplemental feed during the winter. One Angus sire was used through artificial insemination on yearling heifers, while two Charolais sires were utilized thereafter in a terminal crossbreeding program. Simmental × Angus heifers were heavier (P<.05) as yearlings and 2-yr-olds and had larger (P<.05) yearling and 2-yr-old pelvic areas than H × A heifers. During the study, S × A cows averaged 33 kg heavier (P<.01) at weaning time than H × A cows. No differences were found (P>.05) in percent calf crop born, percent calf crop weaned or calving difficulty between the two cow breeds. During the 3 yr evaluated, S × A cows produced more milk (P<.01) than H × A cows. Calf birth weight, gain to weaning, and weaning weight were greater (P<.01) for the S × A dams. Two nutritional levels (“regular” vs high) were compared within cow breeds. No difference (P>.05) due to nutrition level was present on reproductive performance, calf birth weight or milk production under conditions of this study. However, both dam breeds on the regular nutritional regimen weaned heavier calves (P<.01) than cows on the high level of nutrition. These results indicate that S × A cows can have greater calf productivity than H × A cows under range conditions, even on a regular nutrition level, if sufficient forage is available.

Mixed Model Methodology for Unifying Within-Herd and National Beef Sire Evaluation

A mixed model has been developed for the unification of beef cattle within-herd evaluations and national beef sire evaluation. The model accounts for both sire and dam effects and is used to obtain predictors of individual animal genetic merit for traits of economic importance. The prime purpose of the unification is to provide a link between herds for determining best linear unbiased predictors (BLUP) of expected progeny differences (EPD) for yearling bulls and heifers that are comparable across herds. The method of unification builds within-herd mixed model evaluation equations for herd dams, contemporary groups and sires on a herd-by-herd basis. Dams and contemporary group equations are absorbed into sire equations for each herd. After absorption, the sire equations are consolidated from all herds to form a set of national sire evaluation equations. Single-trait BLUP are determined for the sires and are used in back-solving for within-herd contemporary group estimates and dam predictors. Young animal EPD for traits of interest are computed as a function of their parent EPD plus their own regressed performance. Sire growth EPD for the 1984 American Hereford and American Angus sire evaluations were determined using this new methodology to develop sire equations consolidated across herds.

Optimal mature size of angus cows for maximum cow productivity

ABSTRACTLifetime maternal performance records of 113 Angus cows born over a 12-year period were used to estimate the relationship between cow size characters, mature size (A) and maturation rate (K), and lifetime maternal performance characters, years in the herd (YH), number of calves (NC), total calf weight (TW), average calf weight at weaning (AW) and calf weight per year in herd (kg/year). Pertinent reproductive management of the herd was: heifers were mated to calve as 2-year-olds; any heifer failing to calve or any cow failing to wean a calf a second time was culled; all matings were to purebred Angus sires. Mean cow mature size was 487 ± 5 kg with a maturation rate of 0·058 ± 0·001. Means for maternal characters were: YH, 7·4 ± 0·4; NC, 6·4 ± 0·3; TW, 1283 ± 71; AW, 200 + 1·8; and kg/year, 173 ±5·1. The correlations between maternal characters and A and K, respectively, were: YH, −0·21, 0·15; NC, −0·21, 0·15; TW, −0·16, 0·12; AW, 0·20, −0·15; and kg/year, 0·05, −004. The regression of maternal characters on mature size was quadratic in every instance with optimal cow size for each character being: YH, 468; NC, 465; TW, 471; AW, 493; and kg/year, 475. The optimal cow size for average weight of calf weaned was 18 to 25 kg heavier than the optimal size for those characters associated with fertility. Relationships between maturation rate and maternal performance were not statistically significant.

The Effect of Cow Size, Milk Yield and Cow Fatness on the Carcass Characteristics and Meat Quality of Their Progeny

Cattle were produced from a foundation herd having a wide range in mature size and milk yield. All heifers were bred to Angus sires to minimize calving problems. All cows were bred to a Simmental sire for second and third calves. Calves (heifers and steers) were weaned at about 6 mo of age and fed a diet largely based on corn silage. Cattle by Angus sires were slaughtered at 10mm backfat thickness evaluated ultrasonically and those by Simmental sires at 7mm. One side of each carcass was separated into fat, lean and bone. The m. longissimus dorsi from the 9–10–11th rib region was removed, vacuum packaged and stored at —29°C for later quality determinations. A 100kg increase in cow weight alone gave calves that were 28kg heavier at slaughter, 14kg more lean tissue, 1.8kg more fat and 3.4kg more carcass bone. Dam's milk yield had no significant effect on carcass tissue yield. A 1mm increase in fatness of dam at calving decreased progeny carcass lean yield by 2.6kg, fat by 0.4kg and bone by 0.8kg. All the cow factors measured (cow size, milk yield, cow fatness) had no significant effect on taste panel scores for flavour, juiciness, tenderness or overall acceptability. There were also no differences between steers and heifers for taste panel scores. It was concluded that cow factors have little overall effect on the final meat quality of their calves when comparisons are made at similar carcass fatness.